Introduction.

In my
previous post, I discussed the idea of regarding quantum states as
representations of Aristotelian potentia. The idea of potentia was introduced by Aristotle to
allow for the possibility for change. Before him, people regarded being
(or actual existence) or non-being (actual non-existence) as the only
options. Aristotle added a third category, potential existence. Every
being has numerous potentia which describe what changes are possible for
that being, and change is simply potential existence becoming actual
existence and vice versa. If we just treat being and non-being as the
only options, then there is a problem when considering change; we have to say
that being becomes non-being and non-being becomes being.

If this were the
case, there is no justification for saying that something has changed.
Rather something would have gone out of existence and something else come
into existence to replace it. I would not be the same person as the
one sitting at my desk who wrote that last sentence; an infinite number of
different mes would have flickered in and out of existence between
these two full stops. This contradicts our every day experience. It is
solved, and to my knowledge no other valid solution has been found, by
Aristotle's proposal of potential existence.

The idea is that something endures throughout all these changes. Aristotle
called this something prime matter, which is pure potentiality.
When united with form by an act, prime matter takes on a particular
shape; but all the potentials in some sense continue to exist within the
object. One of these potentia is actual at any given moment, and that is
what we see and touch. But the matter doesn't have to be in that state;
it has the potential to adopt many different shapes, and so those
different possible states exist potentially within the matter. The matter
itself changes, in that there is a movement between potential and actual
existence within it. So change doesn't involve movement from non-being to
being; it involves the movement from one type of being to another; from
potential being to actual being.

A corollary of this is that there are two aspects to a substance; matter,
which represents potentiality, which is constant but can take on different
shapes, and form, which represents actuality, which describes which shape
happens to be adopted by the matter in any given moment, as well as the
other possible potentia it could adopt while remaining the same being.

As is well known, in the early modern period, Aristotle's metaphysics was
overthrown. Aristotle got things wrong, and one of his biggest mistakes
was to reject Pythagoras' and Plato's suggestion that physics ought to
be understood geometrically. When geometrical physics was resurrected in
high medieval Europe, the early pioneers in Oxford and Paris thus needed
to go beyond Aristotle to find some analogy to explain what they were
doing. They turned to the newly invented and exciting clockwork clocks,
with their dependence on intricate and finely engineered moving parts.

When the work of these pioneers was given new impetus in the early modern
period (with medieval philosophy and Aristotelian basis now generally
spurned in favour other classical traditions, nominalism and empiricism),
this analogy was taken as reality, and the mechanical philosophy was born.

Key Aristotelian principles, such as form and finality (which
I believe are also necessary to understand quantum physics; but that's not
today's topic) were chucked out of the window. With them went Aristotle's
notion of potential existence. Unable to describe change in this way,
modern philosophers have in effect been reduced to either saying that
change is impossible or constancy is impossible; or by mixing the two
proposals in some way. For example, the mechanical philosophy denies the
possibility of change in (fundamental) substances as impossible, and
denies the possibility of constancy in location (indeed, it cannot even
define what constancy in motion means, given the identity between
different reference frames).

What replaced Aristotle was the mechanical philosophy. In this philosophy,
matter could be reduced to its constituent and most fundamental
parts, which some writers
called atoms and others corpuscles. There is a subtle difference between
the two in the technical literature of the period, but I'll ignore that
distinction and just use the word corpuscle, since atom has come
to have a very different meaning in modern science. These corpuscles are
the most fundamental objects in nature. So I will use the less familiar
word (at the risk of using it in a slightly different sense to how it was
used in the sixteenth and seventeenth century literature) to avoid
confusion with the modern concept.

In the mechanical world view, corpuscles
have a limited number of primary properties: location, velocity, dimension,
mass, and maybe a few others. They are basically just localised lumps of
matter, which interact solely through collisions.
These properties are seen as being inherent to the
corpuscles. There were also secondary predicates, such
as colour, texture, sound, and others, which were added to objects when
filtered by our senses. The diverse array of different objects we see
around us just come from different arrangements of these corpuscles.
Change just comes from movement of corpuscles from one arrangement to
another. The corpuscles themselves are unchanging, except in their
location and velocity. They cannot come into or out of existence; they
cannot morph from one form to another. There is only actual existence.
Moreover, their motions are completely deterministic. Know everything
about the universe at one moment of time, apply the correct laws of motion,
and with enough computing power you can correctly calculate the state of
the universe at any future or past moment of time.

There are philosophical issues with the mechanical world view
(particularly related to the philosophy of mind and ethics), but these
were either ignored and neglected because it seemed to work so well
in describing physics, or people tried to modify the mechanical picture
to solve these problems (for example Cartesian dualism, or Kantian
idealism), and just created new ones in their place. Scientific problems
with the picture also emerged. The action at a distance implied by
Newton's gravity caused some headaches; more importantly the
demonstration of the reality of extended fields in electromagnetism by
Faraday, Maxwell and others also confused the picture. The mechanical
philosophy had to be adapted to accommodate this. But it continued to have
its successes, and physics inspired by this philosophy continued to make
progress, culminating in Einstein's theory of general relativity.

But then came quantum physics, the principle of superposition, and
the Pauli exclusion principle. This is a headache to the mechanist,
because there are properties of a being which can't be held
simultaneously. We like things to be nicely defined; but suddenly we find,
for example, that particles don't have definite spin in one particular
direction. Everything we can measure must have actual existence.
Everything that exists must be either spin up or spin down
along every possible axis. (The only alternative to existence
is that it doesn't exist, and if a property can be measured then it
must be an actual predicate of the object.)
So far there is no problem with the mechanical philosophy.
But then we add the final ingredient: if the spin is defined along one
axis, then it is undetermined along every other axis, until someone
measures it when it has a definite value.
We find a particle which
exists but is not spin up on a particular axis, nor is it spin down,
but is perhaps neither of
them or both of them at once. To the mechanist, this is a contradiction.
Something that exists must be in a definite state, and yet this particle isn't
in a definite state. Something could be in a indefinite state if it doesn't
exist, and yet this particle certainly exists because we can measure it.
It therefore has some of the properties we expect of being, but not all of
them, and some of the properties we expect of non-being, but not all of
them. It is in a half-way house between being and non-being, not really
fitting in either category.

The Aristotelian, however, has things easier. He has one more option:
potential being. Something in actual
existence can't exist simultaneously in contradictory states; but its
potentia can be, and usually are, mutually exclusive states. The
Aristotelian would phrase it as follows: Everything we can measure must
have either actual or potential existence. Everything that exists must be
potentially either spin up or spin down along every axis. One of those
states is actual, and the rest are potential.
The particle exists actually in a spin up or spin down state along a
particular axis. It also has potential existence, and these potentia
include the spin-up and
spin-down states in the direction we are studying. It be potentially
spin-up and spin-down at the same time; there is no difficulty in
two of the potentia being in contradictory states. Thus for the
Aristotelian, qualities such as this (superposition of states)
are no problem at all. Because the Aristotelian also allows for things to
have potential existence, he finds himself at home in situations which
the mechanist, indeed all modern philosophers, can't cope with.

I am not the
first person, nor the only one, to identify quantum
mechanical states with Aristotelian potentia. In particular,
a work by Gil
Sanders has recently come to my attention. In the rest of this post,
I want to briefly comment of the strengths and weaknesses of that article.

Summary of article

One thing I haven't dwelt on much in my own work is the measurement
problem in quantum mechanics. I'll explain why I don't tend to dwell on it
much a little later.

There are different forms of the measurement problem in quantum mechanics (QM),
but the most important (in my view) can be phrased as follows. In QM,
the particle's state is governed by the wavefunction, which can be
regarded as a superposition of the fundamental states. It basically
describes the likelihood (using the terminology I use
here)
or amplitude (using more conventional terminology) that each state is
occupied by the particle is at any given time. There is a separate
wavefunction for each
particle in QM; QM borrows from classical mechanics the premise that
the fundamental building blocks of matter are indestructible. This
wavefunction evolves according to a differential equation, and is
therefore deterministic. This equation is the Schroedinger equation in
non-relativistic quantum mechanics, or the Klein-Gordon or Dirac equations
in relativistic quantum mechanics. However, when we take a measurement,
there is
indeterminacy: the particle magically drops into one state or another.
The wavefunction is affected by the act of measurement. It no longer
evolves deterministically, but is suddenly forced into a particular state.
Which state is chosen is unpredictable, and occurs according to the
distribution computed in the likelihoods in the wavefunction.

The dichotomy about the deterministic evolution of the wavefunction and
the unpredictable nature of measurement is this form of the measurement
problem. What is it about the problem of measurement that causes this
collapse of the wavefunction? Is consciousness somehow involved? The
separation of scales between the microscopic and microscopic?

The article lists four basic problems involved in the measurement
problem.

What does the wavefunction represent?

What constitutes a measurement?

When does the wavefunction collapse?

What happens with entangled particles?

The article next considers some of the most popular philosophies of QM,
focussing on the Copenhagen interpretation, the Bohm interpretation, and
Everett's many worlds interpretation.

Does the wavefunction collapse when there is a measurement? This leaves
the notion of measurement vague and undefined. Also, it seems
problematic and counter-intuitive to say that no object exists until we
observe it. What about other observers? Does my wife exist when I can't
see her? (It would be interesting to see someone use that argument
in a courtroom in defence of their adultery.) Do I exist when my wife
can't see me?

Does the wavefunction collapse at the level of consciousness. But then
how do we define consciousness?

Does the wavefunction collapse when a microscopic system comes into
contact with a macroscopic system? But then, how do we draw a line
between the two? After all, QM is meant to describe both the microscopic
and macroscopic worlds.

Can we use an empirical definition? Wavefunctions collapse when
wavefunctions collapse. But this circularity doesn't allow a theoretical
understanding. We can't predict wavefunction collapse in the equations
of QM.

Could the wavefunction describe some real entity? This would imply that
there are real entities without definite properties. On the other hand,
if it doesn't, how is the wavefunction linked to the real object of
scientific study?

The de Broglie-Bohm interpretation posits a deterministic wavefunction
spreading over all space. This wavefunction really exists, but comes at
the cost of locality. It guides particles with definite trajectories.
By creating the two levels of wavefunction (which we don't observe, but
is represented by the equations of QM) and particle (which we do observe,
but is absent in the equations), it denies that the collapse of the
wavefunction occurs. Properties are not intrinsic to the particles but
are contextual, depending on the circumstances at the time of its
measurement. But then we encounter the issue of how the unobservable
guiding wave is linked and can affect the observable particle.

The many worlds interpretation treats the wavefunction as the universe.
Rather than a collapse of the wavefunction, the universe splits into
different branches. We only see one of these branches (which one is
"random"), so it appears
to us as though the universe is indeterminate; however as a whole the
universe is determinate, and still largely mechanical. But to talk about
probability requires a basis to describe the range of measurement
outcomes, which can only be determined through a decoherence process.
But this decoherence can only occur if the universe is indeterminate.

This provides a good summary of the major interpretations, and why none
of them are especially appealing. I have a few quibbles about the
discussion of the many-worlds interpretation and how probabilities
emerge from it. I personally feel that this interpretation is stronger in
this regard than the author of the article gave credit to it. (I still
don't agree with this interpretation, but it is harder to pick apart than
the rest of the modern and post-modern interpretations.)

There then follows in the article a discussion of mathematics in physics,
and how things such as causal powers and teleology were left on the
wayside because they don't really fit in with the mathematical description.
However, metaphysics is important. Physics only partially describes
reality. If some aspects of metaphysics can't be
(easily) treated mathematically, then we might expect the mathematical to
create various paradoxes as we get down to the more fundamental level.
This is especially true if we adopt an incorrect metaphysics. Since the
time of Galileo and Newton, the primary way of thinking about the world
has been mechanical, which worked well up to the time of Maxwell.
They insisted that the physical world should display a precise
mathematical structure. The success of classical physics seemed to
render Aristotle's more intricate metaphysics, with its numerous
non-mathematical elements, redundant.

There are, however, significant philosophical problems inherent in the
mechanical world view. The mind-body problem is one of them. This states
that

excluding qualities from the world is wrought with problems. If
matter is essentially quantitative and devoid of any qualitative features,
then it is impossible to
reduce a mind that is essentially qualitative to something that is essentially non-qualitative. At
best something quantitative can be correlated to some quality insofar as it has a power to produce a quality, but this power is not itself a quality (unless we accept Aristotle’s qualitative account of causal powers) so it can only produce a quality in something that is already essentially
qualitative.

Equally, there are issues with causality and causal powers. The denial of
final causality (that beings have an inherent tendency towards particular effects) leads to
the denial of any inherent rationality in our understanding of nature at
all, as Hume most clearly expressed. Even the concept of "laws of nature"
is not clearly defined in a mechanical point of view. If the laws of
nature are a description of physical regularities, then they do not
explain them.

However, that quantum mechanics seems weird means that the paradox is
almost certainly not in QM itself, but in the link between QM and the
metaphysics used to interpret it. Thus we should not trust any mechanical
metaphysics. Even though most of the world regards these philosophies
as "scientific", they are contradicted by the best science.

The article then proceeds to give a good account of the Aristotelian
account of potentia, and how modern interpretation of physics has
created problems for itself by denying it. It raises one important point
missing from my discussion above: that, in an Aristotelian metaphysics,
complex substances are substances in their own right. They are not simply
the sum of their parts. Water is not hydrogen plus oxygen; but has its own
structure and energy levels. The hydrogen and oxygen lose their own
independent actual existence when they join together into a water molecule.
Instead they can be said to exist virtually
within the water. This virtual existence is actualised, for example, when
the water is split by an electrical current. This is in contrast to the
mechanical philosophy, which states that matter is no more than the
sum of its parts.

This hylomorphic construction of nature allows a gradual spectrum of
material beings, ranging from pure potency (prime matter) to pure
actuality (God). It has greater actuality if it has a more determinate
form. The closer one gets to prime matter, the more one would expect
something to be dominated by potency. The less the potentia are obvious,
the more definite an being will seem to be. As we come closer to pure
potency, then we would expect things to become less determinate and fixed.

As Aristotle noted, matter is "universal and indefinite" (Metaphysics)
so when you destroy a substance to break it down to its smaller parts,
hylormophism predicts that you will find
higher levels of potency because you are getting closer to prime matter.
This is precisely what we find in QM. The macroscopic world has more
actuality, which is why we experience it as more definite or determinate,
whereas the microscopic world has far less actuality, thereby creating far
less determinate behavioural patterns.

Aristotle's prescription accounts naturally for the counter-intuitive
aspects of QM. For example, the wave-function naturally needs to be
linked to some physical reality; otherwise there is no good reason why it
should be able to make such successful predictions. Neither should we give
the states that it describes an actual existence. All the common
interpretations of QM
interpretations implicitly
suppose an anti-Aristotelian metaphysics so they are left to choose between
giving the wavefunction actual existence or denying that it exists at all.
But this is a false dilemma, because potency is also a real feature of
reality.

This view reinterprets superpositions as being the potentials of a thing or state, not as
actual states in which all possibilities are realized. Unlike its rivals, Aristotelianism does not
posit new entities to solve a very specific empirical problem. The act-potency distinction is
something that permeates throughout all levels of reality already, it is not something conveniently used to fit into the facts but is necessary to account for the facts. So when Aristotelians appeal
to potencies to account for QM, it is not ad hoc or lavish but has a natural explanatory advantage
over competing interpretations.

Measurement can be described as an event when something perceptible
comes into contact with something imperceptible. Perceptible objects
have less potency, while imperceptible objects greater potency.

The wavefunction collapses when a potency is actualised.

Entanglement is allowed because, although action at a distance is not
allowed for actual states, there is nothing to stop potencies being
eliminated at a distance.

Aristotle's world-view thus provides a very plausible reply to the metaphysical
problems raised by the measurement problem. If the microscopic world is
indefinite, then so should the macroscopic world be. In a mechanical
conception of matter, all macroscopic devices are reducible to their
microscopic particles. If all microscopic particles are equally actual, then
we would either have to say that all things are determinate (many world)
or all things
indeterminate (quantum idealism). The first of these posits unobservable
entities, the second is subject to Descartes' problem of linking the mental and
physical worlds. But if Aristotle's conception is true, then the combination
of indeterminacy and determinacy we observe is roughly correct.

Criticisms

I think that the article raises many good points; I agree with its overall
conclusion that many of the difficulties in QM disappear once we adopt an
Aristotelian metaphysic. I have a few minor quibbles here and there, but
two major concerns with the paper.

The article makes frequent mention of Bell's theorem. This is not
surprising, since it is very relevant to the topic. Bell's theorem
is related to entangled particles. These are two particles whose
properties are linked together, for example the results of some decay
process which must have opposite spin. We don't know the spin until we
measure one of them; when we do so the spin of the other particle is
determined, even if it is at the other end of the universe.
Both wave-functions must collapse simultaneously. The obvious way around
this is to posit that each particle has various hidden variables; the
unpredictability of measurement is because we don't know what these
variables are. Bell's theorem creates a series of inequalities based on
a number of assumptions, including:

The particles exist with definite (but hidden) properties,
and we should treat the uncertainty caused by the hidden variables using
classical probability.

The particles can't communicate at a distance.

If Bell's inequalities fail, then at least one of the axioms must be
false. Since the other axioms are also necessary for quantum mechanics as
a whole, the focus falls on these two. The first of these is often called
scientific realism; the idea that the wave-functions represent particles
with real and determined properties, and a given number of particles have
definite spin in each direction. From this frequency distribution we can
reconstruct the probabilities. In other words, the idea is that there is
an underlying classical mechanical (or similar wholly deterministic) system,
and the apparent indeterminacy
is simply caused by us not knowing all the details of the underlying
system.

Bell's inequality is experimentally violated, which means (according to
the standard interpretation) either realism or locality must be false.
Neither are very appetising: a breakdown in locality seems to violate
special relativity; a break down in realism leads us with no clue at all
as to what is going on.

The article, however, classes this as a dichotomy between determinism and
locality.

For example, Bell’s theorem showed that no interpretation can have both
locality and determinism as classically conceived. If locality is
abandoned then particles can causally affect another particle
at a distance without any intermediary contact between particles
(aka spooky action at a distance). But if we reject determinism for
locality, then the world is indeterministic and it defies a full
scientific explanation.

I think that there might be a confusion between two senses of the word
determinate here. Bell's theorem strictly refers to objects with
determinate properties, i.e. all the properties of an object are
specified. However, determinism by itself is the belief that events
are predictable (if we knew the starting conditions to enough precision).

Indeterminate in the sense of unpredictable is not inconsistent with a
full scientific explanation or even with causality. Modern descriptions of
causality (excluding Hume's nonsense), based on the mechanical philosophy,
generally adopt the position that
every change in motion is caused by an event; while every event is caused
by the interaction between different particles. For example, we might
have two particles colliding (an event) and then moving off in a different
direction (change in motion).
This has a problem in QM because it is no longer true that every event has
a cause. Some events (such as spontaneous emission) seemingly have no
explanation.

However, the classical position of efficient causality is that every
substance in a particular state has as its cause another substance (or
substances). So, for example, when an up quark spontaneously decays into
a W+ Boson, and down quark (beta radioactive decay),
the efficient cause of the down quark is the up quark in whichever
potentia it happened to be in. Classical causality thus skips the
middle-man of the event; it does not require that events need to be caused.
Obviously we can extend the theory to also describe the circumstances
when actualisation of potentia could occur, which would cover the use
of events in the mechanical philosophy, but need not bring in the extra
philosophical baggage of mechanism such as determinism.

To my mind, the solution to Bell's theorem is straight forward. In the
derivation of his inequalities, Bell assumed that uncertainty
concerning the hidden real substratum of matter should be parametrised
using classical probability; assuming that all the predicates of the
particle have actual values in the hidden substratum, and we can
just counting how many particles of each type there are. If, however,
classical probability doesn't apply to the hidden substratum, then Bell's
derivation breaks down. The issue is not with realism, but in treating
uncertainty classically. If a quantum particle needs to be described both
in terms of which state it is in and in which basis that state exists,
and the possible bases are not unique and not orthogonal, then the
axioms of classical probability break down. Bell has a hidden assumption
(not usually stated):
that uncertainty in a physical process should be parametrised using
probabilities, and it is this assumption rather than locality or realism
which is violated.

The second major problem I have with the article is more fundamental. It
is based on outdated physics.

Whenever I read a philosophy of physics article which discusses the
Schroedinger equation, except to say that it is irrelevant, I throw my
hands up in the air and run around screaming.
Quantum mechanics is wrong. It is
usefully wrong, because it led us to quantum field theory, and many of
its concepts are carried onto into field theory, but it is still
wrong. Although many people I have read regard quantum field theory (QFT)
as little more than QM updated to handle fields, this view certainly
understates the differences. For one thing, the objects modelled in QFT
are not classical fields; nor are they classical particles; they are
something wholly different.

Quantum mechanics removes some assumptions of mechanism, but retains some
others. It adopts the idea of potential and actual states, contrary to
mechanism. But it retains various other mechanistic premises. The most
important of these is the assumption that the fundamental building
blocks of matter are indestructible. Each wavefunction in QM describes
the states in which a single particle could exist in an external
potential energy. There is no possibility for that particle to come into
or out of existence. Decay processes, absorption processes, annihilation
processes and so on cannot occur in quantum mechanics. Yet these are
observed constantly and unpredictably.

A differential equation, such as the Schroedinger equation, also cannot
cope with discontinuous events such as particle creation or annihilation.
The true theory of nature thus cannot be reduced to any differential
equation; it is not merely a case of fine tuning the Schroedinger equation
until we get something that works.

Quantum mechanics is known as first quantisation. It expresses observables
in terms of the eigenvalues of operators. The eigenstates of those
operators describe the
possible potentia of particles, and particles move between those states,
with amplitudes given by the wavefunction. But this is not enough. If
particles can be created and destroyed, then we need operators describing
the creation and annihilation of particles. Particles are now
represented by these creation operators rather than probability amplitudes.
The operators act on a space which basically counts how many particles we
have of each type at any given moment of time.

The time evolution operator is constructed from these creation and
annihilation operators. It acts on the state vector, but there is no
deterministic evolution of the state at all. Rather, any "path" to get
from A to B is possible. Each path consists of the creation
of annihilation of different particles. Each decay, emission or absorption
in this process is an unpredictable event, although it still has an
efficient cause (in that each new particle emerges from something else).
To calculate the total amplitude for the final result, we need to sum
over the likelihood for each possible path weighted by the appropriate
factor.

The measurement problem is thus drastically changed. There is no
deterministically evolving wavefunction coupled with an indeterminate
measurement process. Rather, everything is indeterminate. There is no
collapse of the wavefunction because there is no wavefunction, at least
not in the sense that there is in QM. What we have in its place is a Fock
state, which describes everything in the universe; and it does not evolve
deterministically as the QM wavefunction does.
I have seen
proposals that collapse occurs with the creation or annihilation event.
If the notion of collapse still makes sense, then this proposal is plausible
to me, and it is not something relevant in QM because QM does not allow for
creation or annihilation events.

However, I am not convinced that we need
collapse of quantum states in QFT at all.
I would rather say that the Fock state represents our knowledge
of the system. The system evolves in one of the many possible ways
allowed in the path integral. We cannot say which one, so there is
uncertainty about future states, which we express in terms of an
amplitude. There is no anomaly in saying that our knowledge changes when
we take a measurement. This explanation again is not really possible
in quantum mechanics, but makes more sense in QFT.

In QFT, we are given an
initial state (which is best expressed as a momentum eigenstate).
What we calculate in QFT is the likelihood that the system
will finish in a particular final state. We calculate this amplitude by
counting how many ways or paths the system can evolve from the initial to
final
state (weighting each path by an appropriate factor). We cannot know what
route the system took to get from A to B. When we want to
calculate the expected value for some property, we multiply the eigenvalue
times the likelihood for the corresponding eigenstate, and sum over all
the options.

When we take a measurement, therefore, what we are asking is `Is there a
particle, when expressed in this basis, in this particular state at the
given time, given that it was in the initial state and the laws of QFT?'
This is a different question than in QM, where what we compute and compare
against experiment are the properties directly, rather than using the
states or potentia as the chief objects of our consideration.

If the question we ask in QFT is `What is the likelihood that this
particle will be in a particular state given what we already know about
the system', then QFT primarily asks about our knowledge of the system,
and our
degree of uncertainty of various outcomes occurring. When we perform a
measurement, our knowledge changes. In this way, what remains of
wavefunction collapse is easy to understand. As is entanglement; for
example, the decay products (say of a spin 0 particle) emerge in some
particular eigenstates (of opposite spin) of some particular basis; and
using the laws of how we compute likelihoods in QFT we can say that for
each state in whatever basis that the first particle could be in, the
chance that the other particle is in the same state is zero. Behind the
scenes, the states are determined at the moment of decay; there is no need
to postulate communication at a distance.

The indeterminacy of QFT means that
we can never be sure how a system will evolve. This means that we can
compute certain results, only varying degrees of uncertainty.
The weirdness of quantum
physics arises from that uncertainty is parametrised using amplitudes
rather than the more familiar probabilities.

There are differences between QM and QFT; and these differences have
important philosophical consequences. QM takes some ideas (such as the
intermediate state between being and non-being) from Aristotelian metaphysics,
and other ideas (such as event causality, or the indestructibility of matter,
or deterministic evolution of a wavefunction) from the mechanical philosophy.
QFT is more like what we would expect in a pure Aristotelian system.
Now, it might be that some
philosophical idea translates directly from QM to QFT. But that need not
be the case. It might also be that the solution to a QM "paradox" is
apparent in QFT but doesn't fit into QM. It thus seems to me foolish to
worry about the philosophy of Quantum Mechanics, since there is no
guarantee that whatever you conclude will carry over to the more advanced
theory. Start with field theory, and build your philosophy on that.

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